Photographing method and electronic device

Abstract

In accordance with an embodiment, a method of operating an electronic device comprising a screen, a first camera, and a second camera, includes: detecting that a zoom ratio gradually changes within a first ratio range, wherein the zoom ratio in the first ratio range is less than an optical zoom ratio of the second camera, and a ratio difference between the zoom ratio within the first ratio range and the optical zoom ratio of the second camera is less than a first value; cropping an image captured by the first camera to obtain a preview image whose field of view (FOV) size gradually changes; and displaying on the screen, the preview image whose FOV size gradually changes.

What is claimed is: 
     
       1. A method of operating an electronic device comprising a screen, a first camera, and a second camera, wherein optical centers of the first camera and the second camera do not overlap, and a focal length of the first camera is less than a focal length of the second camera, the method comprising:
 detecting, by the electronic device, that a zoom ratio gradually changes within a first ratio range, wherein the zoom ratio in the first ratio range is less than an optical zoom ratio of the second camera, and a ratio difference between the zoom ratio within the first ratio range and the optical zoom ratio of the second camera is less than a first value; 
 cropping an image captured by the first camera to obtain a preview image whose field of view (FOV) size gradually changes, wherein an FOV center of the preview image, whose FOV size gradually changes, gradually approaches or gets away from an FOV center of the second camera; and 
 displaying, by the electronic device on the screen, the preview image whose FOV size gradually changes. 
 
     
     
       2. The method according to  claim 1 , wherein:
 in the first ratio range, a larger zoom ratio leads to a smaller FOV of the preview image, and indicates that the FOV center of the preview image is closer to the FOV center of the second camera; and 
 in the first ratio range, a smaller zoom ratio leads to a larger FOV of the preview image, and indicates that the FOV center of the preview image is farther away from the FOV center of the second camera. 
 
     
     
       3. The method according to  claim 1 , wherein the zoom ratio changes within the first ratio range by gradually increasing in the first ratio range; and
 the FOV center of the preview image, whose FOV size gradually changes, gradually decreases and gradually approaches the FOV center of the second camera. 
 
     
     
       4. The method according to  claim 3 , further comprising:
 displaying, by the electronic device, a preview image of a first FOV on the screen before detecting that the zoom ratio gradually changes within the first ratio range, wherein the preview image of the first FOV is from the first camera, and a center of the first FOV is consistent with an FOV center of the first camera. 
 
     
     
       5. The method according to  claim 3 , further comprising:
 detecting, by the electronic device, that the zoom ratio increases to be greater than the optical zoom ratio of the second camera; and 
 displaying a preview image of a second FOV on the screen, wherein the preview image of the second FOV is from the second camera, and a center of the second FOV is consistent with the FOV center of the second camera. 
 
     
     
       6. The method according to  claim 1 , wherein the zoom ratio changes within the first ratio range by gradually decreasing in the first ratio range; and
 the FOV center of the preview image, whose FOV size gradually changes, gradually increases and gradually gets away from the FOV center of the second camera. 
 
     
     
       7. The method according to  claim 6 , further comprising: displaying, by the electronic device, a preview image of a third FOV on the screen before detecting that the zoom ratio gradually changes within the first ratio range, wherein the preview image of the third FOV is from the second camera, and a center of the third FOV is consistent with the FOV center of the second camera. 
     
     
       8. The method according to  claim 6 , further comprising:
 detecting, by the electronic device, that the zoom ratio decreases to be less than a minimum ratio in the first ratio range; and 
 displaying a preview image of a fourth FOV on the screen, wherein the preview image of the fourth FOV is from the first camera, and a center of the fourth FOV is consistent with an FOV center of the first camera. 
 
     
     
       9. The method according to  claim 1 , wherein
 cropping the image captured by the first camera comprises determining a position of a cropping area based on the zoom ratio, an imaging deviation offset at a first distance, and an eccentric factor α at the zoom ratio; and 
 the first distance is a detected distance between the electronic device and a scene, the imaging deviation at the first distance comprises a first deviation and a second deviation, and the first deviation and the second deviation are respectively deviations of a center of the image captured by the first camera relative to a center of an image captured by the second camera in an X-axis direction and a Y-axis direction of an image coordinate system; and 
 in the first ratio range, a larger zoom ratio leads to a larger eccentric factor, a smaller zoom ratio leads to a smaller eccentric factor α; and the eccentric factor is greater than 0 and less than 1. 
 
     
     
       10. The method according to  claim 9 , wherein on a plane of the image captured by the first camera, an X-coordinate value and a Y-coordinate value of an upper-left corner of the cropping area are determined as follows:
 X-coordinate value=(1−1/R)*w/2+total_x*α; and 
 Y-coordinate value=(1−1/R)*h/2+total_y*α, wherein 
 
       R is the zoom ratio, total_x is the first deviation, total_y is the second deviation, a is the eccentric factor, and w and h are respectively a width and a height of the image captured by the first camera. 
     
     
       11. The method according to  claim 1 , wherein the method further comprises:
 driving a motor of an optical image stabilization (OIS) system to move a lens of the first camera or a lens of the second camera in the first ratio range, wherein:
 an offset between the optical center of the second camera and the optical center of the first camera gradually increases or decreases as the lens of the first camera moves, and the offset is less than an initial offset between the optical centers of the first camera and the second camera, and 
 in the first ratio range, a smaller zoom ratio leads to a larger offset, and a larger zoom ratio leads to a smaller offset. 
 
 
     
     
       12. The method according to  claim 11 , wherein:
 the zoom ratio changes within the first ratio range by gradually increasing in the first ratio range; and 
 driving the motor of the OIS system comprises:
 driving the motor of the OIS system to move the lens of the second camera to move in a direction perpendicular to an optical axis and toward the first camera, or 
 driving the motor of the OIS system to move the lens of the first camera to move in a direction perpendicular to the optical axis and toward the second camera, wherein the offset between the optical center of the second camera and the optical center of the first camera gradually decreases with a movement of the lens of the first camera or the lens of the second camera. 
 
 
     
     
       13. The method according to  claim 11 , wherein:
 the zoom ratio changes within the first ratio range by gradually decreasing in the first ratio range; and 
 driving the motor of the OIS system comprises:
 driving the motor of the OIS system to move the lens of the second camera to move in a direction perpendicular to an optical axis and away from the first camera, or 
 driving the motor of the OIS system to move the lens of the first camera to move in a direction perpendicular to the optical axis and away from the second camera, wherein the offset between the optical center of the second camera and the optical center of the first camera gradually increases with a movement of the lens of the first camera or the lens of the second camera. 
 
 
     
     
       14. The method according to  claim 1 , wherein cropping the image captured by the first camera comprises performing eccentric cropping, wherein the eccentric cropping shifts a center of a cropping area away from a center of the image captured by the first camera. 
     
     
       15. An electronic device, comprising:
 a screen; 
 a first camera; 
 a second camera, wherein optical centers of the first camera and the second camera do not overlap, and a focal length of the first camera is less than a focal length of the second camera; 
 a processor coupled to the screen, the first camera and the second camera; and 
 a memory operatively coupled to the processor with instructions stored therein, wherein the instructions, when executed by the processor, cause the processor to:
 detect that a zoom ratio gradually changes within a first ratio range, wherein the zoom ratio in the first ratio range is less than an optical zoom ratio of the second camera, and a ratio difference between the zoom ratio within the first ratio range and the optical zoom ratio of the second camera is less than a first value, 
 crop an image captured by the first camera to obtain a preview image whose field of view (FOV) size gradually changes, wherein an FOV center of the preview image, whose FOV size gradually changes, gradually approaches or gets away from an FOV center of the second camera, and display the preview image whose FOV size gradually changes. 
 
 
     
     
       16. The electronic device according to  claim 15 , wherein the zoom ratio changes within the first ratio range by gradually increasing in the first ratio range; and
 the FOV center of the preview image, whose FOV size gradually changes, gradually decreases and gradually approaches the FOV center of the second camera. 
 
     
     
       17. The electronic device according to  claim 15 , wherein the zoom ratio changes within the first ratio range by gradually decreasing in the first ratio range; and
 the FOV center of the preview image, whose FOV size gradually changes, gradually increases and gradually gets away from the FOV center of the second camera. 
 
     
     
       18. The electronic device according to  claim 15 , further comprising:
 an optical image stabilization (OIS) system comprising a motor coupled to a lens of the first camera or a lens of the second camera, wherein:
 the instructions, when executed by the processor, further cause the processor to cause the motor to move the lens of the first camera or the lens of the second camera, 
 an offset between the optical center of the second camera and the optical center of the first camera gradually increases or decreases as the lens of the first camera moves, and the offset is less than an initial offset between the optical centers of the first camera and the second camera, and 
 in the first ratio range, a smaller zoom ratio leads to a larger offset, and a larger zoom ratio leads to a smaller offset. 
 
 
     
     
       19. The electronic device according to  claim 18 , wherein:
 the zoom ratio changes within the first ratio range by gradually increasing in the first ratio range; and 
 the instructions, when executed by the processor, further cause the processor to:
 drive the motor of the OIS system to move the lens of the second camera to move in a direction perpendicular to an optical axis and toward the first camera, or 
 drive the motor of the OIS system to move the lens of the first camera to move in the direction perpendicular to the optical axis and toward the second camera, wherein the offset between the optical center of the second camera and the optical center of the first camera gradually decreases with a movement of the lens of the first camera or the lens of the second camera. 
 
 
     
     
       20. The electronic device according to  claim 18 , wherein:
 the zoom ratio changes within the first ratio range by gradually decreasing in the first ratio range; and 
 the instructions, when executed by the processor, further cause the processor to:
 drive the motor of the OIS system to move the lens of the second camera to move in a direction perpendicular to an optical axis and away from the first camera, or 
 drive the motor of the OIS system to move the lens of the first camera to move in the direction perpendicular to the optical axis and away from the second camera, wherein the offset between the optical center of the second camera and the optical center of the first camera gradually increases with a movement of the lens of the first camera or the lens of the second camera. 
 
 
     
     
       21. A non-transitory computer-readable storage medium with instructions stored therein, wherein, when the instructions are executed by a processor, the processor is enabled to perform:
 detect that a zoom ratio of a first camera or a second camera gradually changes within a first ratio range, wherein the zoom ratio in the first ratio range is less than an optical zoom ratio of the second camera, and a ratio difference between the zoom ratio within the first ratio range and the optical zoom ratio of the second camera is less than a first value, wherein optical centers of the first camera and the second camera do not overlap, and a focal length of the first camera is less than a focal length of the second camera; 
 crop an image captured by the first camera to obtain a preview image whose field of view (FOV) size gradually changes, wherein an FOV center of the preview image, whose FOV size gradually changes, gradually approaches or gets away from an FOV center of the second camera; and 
 cause the preview image whose FOV size gradually changes to be displayed. 
 
     
     
       22. The non-transitory computer-readable storage medium of  claim 21 , wherein when the instructions are executed by the processor, the processor is further enabled to perform:
 cause a motor of an optical image stabilization (OIS) system to move a lens of the first camera or a lens of the second camera, wherein
 an offset between the optical center of the second camera and the optical center of the first camera gradually increases or decreases as the lens of the first camera moves, and the offset is less than an initial offset between the optical centers of the first camera and the second camera, and 
 in the first ratio range, a smaller zoom ratio leads to a larger offset, and a larger zoom ratio leads to a smaller offset.